def A():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No")
A() def A():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No") A x = int(input()) x int(input()) int input() input if x >= 30:
        print("Yes")
    else:
        print("No") x >= 30 x 30 print("Yes") print "Yes" print("No") print "No" A() A def A():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No") def A():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No") A
def A():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No")
A()